The separation of a flowing medium mixture has very diverse applications. For purposes of the present disclosure, the term “medium mixture” means a mixture of solid and/or liquid and/or gas particles of micron or sub-micron size dispersed in at least one liquid or gas. Examples are a gas/gas mixture, a gas/liquid mixture or aerosol, a liquid/liquid mixture, a gas/solid mixture, a liquid/solid mixture, or such a mixture provided with one or more additional fractions. The separation of a flowing medium mixture is, for instance, known from various applications of liquid cleaning, (flue) gas cleaning and powder separation. Separation of fractions with a great difference in particle size and/or a great difference in mass density is relatively simple. Large-scale use is made for this purpose of processes such as filtration and screening. In the separation of fractions with a smaller difference in mass density use is made of chemical separating techniques and/or separating techniques such as sedimentation and centrifugation. Certainly when processing large volumes of medium mixture, chemical separating techniques are less economic and usually also less environmentally-friendly. Separating fractions by means of sedimentation requires time and, when processing larger volumes of medium mixture, makes it necessary to make use of voluminous reservoirs which is, among other things, expensive. Another per se known technology makes use of the differences in mass density of the fractions for separating by applying a centrifugal force to the mixture by causing the mixture to rotate in a centrifuge or a cyclone. This technique is not usually sufficiently selective to realize a separation of the desired level in a short time.
A device of the type stated in the preamble hereinabove is described in Netherlands Patent Application No. 8700698. This device comprises rotating means in the form of a rotating assembly of feed channels for rotating the flowing mixture for separating, a feed for the medium mixture to be separated connecting to the rotating means, and an outlet connecting to the rotating means for discharging the fractions of the separated medium mixture. In a rotating feed channel, the heavier fraction of the mixture for separating is moved further outward toward the wall of the rotating feed channel than the lighter fraction under the influence of the centrifugal force thus resulting in a separation. A drawback of the device from Netherlands Patent Application No. 8700698 is that the device can only be used at relatively low pressures, whereby separation proceeds more slowly than is desirable. The selectivity of the separation is also capable of improvement.
A similar device is disclosed in WO 2005/118110A1. This document on page 3, lines 3-5 mentions the possibility of carrying the medium to be separated through the feed channels under turbulent flow conditions, although laminar flow in the feed channels is preferred. Dependent on the particular process conditions, the device (and particularly the channel dimensions) can be selected accordingly.